Apparatus for producing cellulose



Feb. 12, 1935. J. J. DE LA RozA, sR 1,991,243

APPARATUS FOR PRODUCING CELLULOSE Filed Dec: 17, 1931 NvENToR" ATTORNEYS Patented Feb. l2, 1,935

' UNITED sijn-'rss APPARATUS FQR PRODUCING CEILULOSE.

Joaquin Julio de la Roza, Sr., Tninucu, Cuba, as-

signor to de la Bona Corporation, Wilmington, Del., al corporation of Delaware Application December 17, 1931, Serial No. 581,638

28 Claims.

This invention relates to apparatus for producing cellulose.

It has for an object to provide for the continuous treatment of cellulose-bearing material so as to accomplish the production of cellulose therefrom at a greatly accelerated rate.

Another object consists in providing for treatment of cellulose-bearing material at a much higher volumetricdensity than has heretofore been practical, whereby the eiliciency and output are greatly enhanced.

Another object consists in providing means for assuring rapid and complete uniform penetration of chemical into the raw material prior to heating to maximum temperature, whereby the treatment time is reduced and the quality of the product improved.

Another object consists in providing apparatus which is relatively simple and inexpensive to manufacture and yet highly productive and eicient in operation.

A further object consists in providing certain improvements in the form, construction and' arrangement of the several parts, and in the steps followed, whereby the above named and other objects may effectively be attained.

A practical embodiment of the apparatus is` diagrammatically represented in the drawing, which representation, when taken in connection with the following description, will set forth my invention for the clear understanding of those skilled in the art.

In the treatment of cellulose-bearing materials, such as wood and various members of the grass family, it has been customary to charge the treating vessels or digesters with a mixture of the fibrous materials and chemical solution, introduced together or separately; and thereafter to apply heat for the treatment, then discontinue theheat, discharge the contents, and repeat the operation by again charging, etc. This procedure has involved serious limitations arising from the interruption of treatment at the time of each discharge, from the lack of uniform quality in the product due to defective and uneven penetration of the raw material by the chemical, and from the limited amount of fibrous cellulose-bearing material treated in a given vessel' or digester ata single time. My invention overcomes these limitations by providing for continuous treatment which mayproceed for hours or months, if desired; and for greatly increasing the volumetric density of the charge during treatment. Heretofore a charge containing about nine pounds of bone dry material per cubic foot has been substantially the maximum in the case of wood, and about half of that in the case of bagasse, cornstalks, and the like, whereas my invention provides for charging to a volumetric density of, Say, twelve to fifteen or even twenty pounds of bone dry material per cubic foot. e

Referring to the drawing, which includes one diagrammatic figure, a treating vessel or digester is denoted by 1. The form of this vessel \is quite unusual but its general construction may substantially follow any well known or approved kind of digester. It should be provided with any usual or desirable equipment such, for instance, as gauges, valves, thermometers, heating appliances, etc. The vessel may either be stationaryl or of the rotating type.

At one end a valve 2 is provided which is operable by the handle 3 for discharging the contents from the vessel. 'Ihis valve may be of usual or suitable form, construction, and operation.

The representation of the vessel in the drawing is broken away intermediate its ends to indicate that it is intended to have a greater proportionate length than shown in the drawing; and I may say that I prefer to make this vessel of relatively great length and small diameter. This may be illustrated by a length of, say, a few hundred feet, and a diameter of, say, a few feet. Such a proportion greatly facilitates the continuous procedure which features my invention and tends to insure that all the material is uniformly treated and occupies a uniform period of time during passage through the treating vessel. It will be understood that the particular dimensions and proportions of the vessel may be varied to suit different factors arising from various methods of treating various materials.

The end of the vessel opposite the valve 2 is provided with an opening 4 which is in communication with a tube 5 that is restricted in area as it approaches the vessel. The drawing is intended to represent a tube taking the form of a truncated cone, but I should say that my invention contemplates any manner of restricting or partially inhibiting the movement of material through the tube toward the vessel, whether such manner involve a regular or irregular restriction of cross sectional area or arrangements for increasing surface friction within the tube, or otherwise.

The larger end of the tube communicates with a cylinder 6 in which is located a piston 'I that is designed to be reciprocated by suitable mechanism, not shown. Two positions of the piston are represented, by way of example, in full and dotted lines. This mechanism is illustrated as one of many suitable kinds adaptable for the purpose of feeding the material.

The cylinder 6 has a port 8 which is in register with a feed or hopper 9, which may be of any well known or approved form.

The vessel l has ports 10 and 11 that are connected by a 'circulating pipe or by-pass 12 in which are located stra'iners 13 and 14, check valves 15 and 16, and manual valve 17. The check valve l5 operates so as to permit entry into the vessel and the check valve 16 operates so as to permit movement from the vessel. The valve 17 is operable so as `to permit movement in either direction. 'I'he particular construction and arrangement of these circulating and feeding parts may. of course, be varied to^suit different conditions. In the drawing I have shown only one pipe l2, but it will be understood that additional pipes, correspondingly arranged, may be provided to connect additional ports in the vessel. As the construction of such additional pipes and ports would, naturally, be the 'same as that shown, it is deemed unnecessary to illustrate them. This pipe 12 permits circulation of the solution from near the discharge end of the vessel to near its inlet end and thus facilitates the action of the chemical and the movement of the material. It also has a certain advantage by way of providing means for affecting the .temperature within the vessel. The valve, 17 may be used for the injection of chemical into the vessel, as may be required, which chemical will pass through the pipe l2 and enter the vessel through the valve 15. The valve 17 may also be used to permit discharge from the vessel of an excess of chemical, if conditions call for it, though it will be understood that, during the operation of the apparatus, the `valve 17 is normally closed. The strainers4 13 and 14 are calculated to withhold the passage of any large particles of the material'through the circulating pipe 12.

The parts hereinabove mentioned are intended to be connected by suitable means such as, for example, flanges and bolts, which are diagrammatically represented 4in the customary way, and which it is regarded as unnecessary to designate by reference numerals.

In operation, the brous cellulose-bearing material, such as bagasse, cotton llnters, cotton stalks, flax stalks or waste, wood,'or any of the suitable undergrowth-woods, grasses or canes, etc., may be broken up or shredded in any of the many well known or approved manners and conveyed, for instance by a conveyor belt, to the hopper 9. 'Ihis material may be mixed with the desired chemical solution, as by use of a tank or spraying apparatus, prior to its conveyance to the hopper; or it may be mixed with such solution at the time it is deposited in the hopper; or

otherwise. I prefer to spray it as it enters the hopper because, the less the mixture is exposed to the air, the less will be the oxidation.

'I'he material is continuously passed 'into the hopper and drops therefrom into the cylinder 6 at a point in front of the piston 7 when the latter is wholly or partly retracted. The recip.

rocating action of the piston will continuously force the material through the tube 5 toward and into the vessel 1. The frictional resistance of the tube 5 will cause the material to be vmore tightly compacted or compressed as it iS urged through the tube so that it will enter the vessel in a condition of quite high volumetric density, e. g., about twenty to thirty or more pounds of dry material to the cubic foot. This density will vary according to different conditions existing in different treating procedures, but I ordinarily prefer to use something over thirty pounds to allow an abundant margin of safety against blow-outs. In order to facilitate this compacting of the material, I prefer to, at the outset, drop a somewhat compact wad of material through the hopper into the cylinder, which wad will act as a plug in the tube 5 and thus initiate the compressing or compacting action described. Such a wad may be made either manually or `by any suitable compressing device which is at hand. Compression of the material to substantially the density indicated will cause each successive charge or batch advanced by the piston to act as a ysort of plug or cork while in the tube 5 and the entrance to the vessel 1 so as effectively to prevent any escape'of the contents from the vessel back into the tube under the influence of the pressure within the vessel. On the other hand, after each successive batch of the material has been forced into the vessel, it will expand or break up so as better to circulate and intermix with the chemical solution. In these respects, the relative cross sectional size of the apparatus at the cylinder 8, the opening 4 and the body of the vessel l are of some importance with respect to the best operation of the apparatus and I have found that the said proportions, substantially as shown in the drawing, vare satisfactory although, of course, various changes in these factors as well as in the particular shape of the parts may be made while retaining the apparatus in operative form and arrangement. It will be observed that, in the drawing, the diameter of the body of the vessel 1 is about twice the diameter of the opening 4, so that the cross sectional area of the former would be about four times that of the latter. Experimental test and practical operation has proved this ratio of one to four to be well within the preferred limits which, for the best operation, should not greatly vary from the ratio named.

This action of the piston on the material not only compacts and moves the material toward and into the vessel l, but it also brings about a' thorough mixing of the chemical solution with the fibrous material by forcing the chemical through pressure into the cells, so as to insure that the chemical has access to and-reaches every portion of the material prior to heating to maximum temperature, thereby preventing injury to the material, expediting the operation, and improving the quality of the product.

As the material is thus compacted and forced through the tube 5, the action may become so severe as to press or vsqueeze some of the chemical solution out of the material; in which event this solution may escape backwardly between the piston and the walls of the cylinder 6.

At the outset of the operation the discharge valve 2 is closed and it is retained in closed position until the vessel has been charged to the intended degree or density, which condition may be indicated by a suitable thermometer, pressure gauge or other recording instrument provided on the vessel. When this stage is reached, the valvev 2 is opened and regulated so that it remains open the proper amount to insure the same rate of discharge, during the continuous operation of the apparatus, as the rate of charge oi the vessel through the tube 5.

It should also be said, though it will probably be understood, that the heating appliances for the vessel are set in operation at#` the outset of the procedure so that a proper treating temperature is maintained Within the vessel, as by injection of steam, jacketing, electricity, or any other approved way.' If the vessel is of the rotating type, as hereinabove indicated, the rotary motion, which may be either continuous in one direction or oscillatory, will have a substantial tendency to agitate the contents of the vessel and thereby promote the treatment.

=It will be seen` that, as already indicated, chemical solution may be admitted or discharged through the valve 17 to'or from the vessel 1. so

that the predetermined and desirable proportion of the mixture ofA material and chemical solution is maintained in the vessel.

Itwill be observed that this apparatus, through the cooperation of the. feeding device and the frictional resistance of the tubular inlet, compacts the material to Asuch a density as satisfactorily to establish a seal during operation while permitting the continuous feed of the material. into the digester. The apparatus also permits digestion at a very high density which promotes emciency by, among other things, preventing `the fresh material from mixing with the partly digested material; and promotes economy in various respects including a saving in heating medium, chemical, recovery processes, radiation losses, labor, time, and avoidance of the re-use of chemical in the form of black liquor or the like. The form of inlet which I have shown complements the form of feeding device to enable a very rapid compacting of the entering material and, thus, the prompt formation of a very satisfactory seal, While likewise permitting the ready passage of the material through the inlet and into the digester proper.

The above described apparatus and method provide for a continuous procedure whereby the material is fed into the hopper 9 and forced by the piston '7 through the treating vessel under predetermined yconditions as to treating chemical, volumetric density, and temperature or pressure. I` contemplate that the apparatus may be operated both day and night for any reasonable period of time. The treated material, as it is discharged from `the vessel, may be subjected to the ordinary finishing steps, or to a further chemical treatment, or may be shipped to some other point for use or further treatment. In case an additional treatment under the action of chemical and temperature is desired, the discharged material may be fed into another similar apparatus and continuously treated as hereinabove described. y

I do not 'intend the invention to be limited as to the particular kind of cellulose-bearing material treated, or as to chemical or temperature employed, but intend the same to have broad application as a continuous procedure in the manufacture of cellulose, preferably under conditions of very high volumetric density of charge. Furthermore, it will be understood that various changes may be resorted to in the form, construction, and arrangement of the several parts, and in the steps followed, without departing from the spirit and scope of my invention; and hence I do not intend to be limited to the details herein shown or described, except as they may be included in the claims.

What I claim is:

1. Apparatus for producing cellulose comprisling, a treating vessel of relatively great length with respect to its diameter, an inlet for feeding material thereinto, and feeding mechanism for urging material through said inlet, said vessel and inlet being substantially horizontally disposed and substantially in axial alinement, said inlet being arranged to resist the passage 'of the material therethrough and constituting the sole support for the material in the inlet.

- 2. Apparatus for producing cellulose comprising, a treating vessel of relatively great length with respect to its diameter, an inlet for feeding material thereinto, and reciprocating feeding mechanism for urging material through said inlet, said vessel and inlet being substantially horizontally disposed and susbtantially in axial alinement, and said inletl being arranged to resist the passage of the material therethrough.

3. Apparatus for producing cellulose comprising, a treating vessel of relatively great length with respect to its diameter, a restricted tubular inlet for feeding material thereinto, and feeding mechanism for urging material through said inlet, the restriction of the inlet serving as the sole support for the material and being sufilcient to'cause. the feeding mechanism to compact the material therein so tightly as to preventescape of contents from the vessel through the inlet under the influence of the pressure in the vessel, said vessel and inlet being substantially horizontally disposed and substantially in axial alinement. l

. 4. Apparatus for producing cellulose comprising, a treating vessel of relatively great length with respect to its. diameter, a restricted tubular inlet forfeeding material thereinto, and reciprocating feeding mechanism for urging material through said inlet, the restriction of the inlet being suilcient to cause the feeding mechanism to compact the material therein so tightly as to prevent escape of contents from the vessel through the inlet under the influence of the pressure in the vessel, said vessel and inlet being substantially horizontally disposed and substantially in axial alinement.

5. Apparatus for producing cellulose comprising, a treating vessel of relatively great length with respect to its diameter, a tubular inlet for feeding material into the vessel, and feeding mechanism for urging material through said inlet, said inlet and feeding mechanism co-operating to compact the material therein so tightly and to such high density as to form a plug unreinforced internally and unsupported except by the inlet walls and adapted to withstand the treating pressure of the vessel and said inlet and feeding mechanism further cooperating to force the material, in compacted condition, through the inlet and into the vessel.

6. Apparatus for producing cellulose comprising, a treating vessel of relatively great length with respect to its diameter, a tubular inlet for feedingmaterial into the vessel, and reciprocating feeding mechanism for urging material through said inlet, said inlet and feeding mechanism cooperating to compact the material therein so tightly vand to such high density as to form a plug unreinforced internally and unsupported except by the inlet walls and adapted to withstand the treating pressure of the vessel, and said inlet and feeding mechanism further coo'perating to force the material, in compacted condition, through the inlet and into the vessel.

. '1. Apparatus for producing cellulose comprising, a treating vessel, a tubular inlet for feeding material into the vessel, the vessel being of relatively great length with respect to its dla- 5 meter and with respect to the length of the inlet, and feeding mechanism for urging material through said inlet, said feeding mechanism and'inlet cooperating to compact the material in the inlet .to a density of at least twenty-five pounds of dry material to the cubic foot.

8. Apparatus for producing cellulose comprising a treating vessel, a tubular inlet for feeding material into the vessel, the vessel being of relatively great length with respect to its diameter 'and with respect to the length of the inlet, and reciprocating feeding mechanismJ for urging material through said inlet, said feeding mechanism and inlet cooperating to compact ythe material in the inlet to a density of at least twenty-five pounds of dry material to the cubic foot.

9, Apparatus forproducing cellulose comprising, a treating vessel, a tubular inlet for feeding material into the vessel, the vessel being of relatively great length with respect to its diameter andl with respect to the length of the inlet, means for supplying chemically treated material to the inlet, feeding mechanism for urging material through .the inlet, said feeding mechanism and. inlet cooperating to force the chemical to penetrate the material and'to compact the material in the inlet so as to form a plug unreinforced internally and unsupported except by the inlet walls and adapted to withstand the treating pressure of the vessel, and said inlet and feeding mechanism further cooperating to force the material, in compacted condition, through the inlet and into the vessel.

l0. Apparatus for producing cellulose comprising, a treating vessel, ,a tubular inlet for feeding material into the vessel, the vessel being of relatively great length with respect toits diameter and with respect to the length of the inlet, means for supplying chemically treated material to the inlet, feeding mechanism for urging material through the inlet, said feeding mechanism and inlet cooperating to force the chemical to penetrate the material and to compact the material in the inlet so as to of itself serve to seal the inlet and withstand the high treating pressure throughout the operation, and said inlet and feeding mechanism further cooperating to force the material, in compacted con.- dition, through the inlet and into the vessel means for supplying heat to the vessel and means for discharging the vessel.

11. Apparatus for producing cellulose comprising, a treating vessel, a tubular inlet for feeding material into the vessel, said inlet and vessel being substantially in axial alinement, and power-driven means for progressively' compacting the material in the inlet to form an internally unreinforced plug to seal the vessel against the treating pressure therein, and for continuously feeding the said compacted material through the inlet into the vessel, whereby the necessity of any other means for sealing the inlet is obviated and a constant flow of compacted material is provided for highly concentrated treatment within the vessel.

12. Apparatus for producing cellulose-comprising, a treating vessel movable in a rotary direction, a tubular inlet for feeding material into the vessel, said inlet and vessel being subr stantially in axial alinement, 'and power-driven yfeeding the said compacted material through the inlet into the vessel; whereby the necessity of any other means for sealing the inlet is obvlated -and a constant flow of compacted material is provided for highly concentrated treatment within the vessel.

13. Apparatus for producing cellulose comprising, a treating vessel movable in a rotary direction, an unobstructed tubular inlet for feeding material into the vessel, means for compacting the material in the inlet and forcing the compacted material therethrough into the vessel, means for supplying heat to the vessel, and means for discharging the vessel.

14. Apparatus for producing cellulose comprising, a treating vessel movable in a rotary direction, an unobstructed tubular inlet for feeding material into the vessel, means for intermittently compacting the material in the inlet and forcing the compacted material therethrough into the vessel, means for supplying heat to the vessel, and means for discharging the vessel.

15. Apparatus for producing cellulose comprising, a treating vessel movable in a rotary direction, an unobstructed tubular inlet for feeding material into the vessel, reciprocating means for intermittently compacting the material in lthe inlet and forcing the compacted material therethrough into the vessel, means for supplying heat to the vessel, and means for discharging the vessel.

I6. Apparatus for producing cellulose comprising, a treating vessel movable in a rotary direction, an unobstructed tubular inlet for feeding material into the vessel, and a reciprocating plunger for compacting the material in the inlet and forcing the compacted material into the vessel.

17. Apparatus for producing cellulose comprising, a treating vessel movable in a rotary direction, an unobstructed tubular inlet for feeding material into the vessel, and a reciprocating lplunger power-driven on its operative stroke for compacting the material in the inlet and forcing the compacted material into the vessel.

18. An apparatus for digesting fibrous or cellular material comprising, a rotatable vessel having an inlet adapted to compact the material its passage through the inlet, said inlet positioned substantially in axial alignment with the vessel, and intermittent feeding .mechanism connected to the vessel.

19. An apparatus for digesting ilbrous or cellular material comprising, a rotatable vessel having an inlet adapted to compact the material during its passage through the inlet, said inlet positioned substantially in axial alignment with the vessel, and an inlet and a discharge mechanism connected to the vessel.

20. A continuous apparatus for digesting fibrous or cellular material comprising, a rotatable digester and means for intermittently charging material to be digested in the form of a plug having a density of at least twenty pounds of dry material to the cubic foot, and discharge means for withdrawing the digested products.

21. Apparatus for producing cellulose comprising, a itreating vessel, a tubular inlet for feeding material into the vessel, and powerdriven means for progressively compacting the material in'the inlet to seal'the vessel against the treating pressure therein, and for continuously feeding the said compacted material through the inlet into the vessel, whereby the necessity of any otherv means for sealing the inlet is obviated and a constant ow of compacted material is provided for highly concentrated treatment within the vessel, means for heating the vessel, and means for dischargingI the digested material from thevessel.

22. Apparatus for producing cellulose comprising, a treating vessel, a tubular inlet for feeding material into the vessel, and reciprocating means power-driven on its operative stroke for progressively compacting the material in the f, and means for discharging-the digested material from the vessel.

23. A digesting apparatus including in combination a digesting chamber, an elongated tapered inlet for said chamber, means for introducing cellulose-bearing material into said inlet, a reciprocating plunger adapted ,to reciprocate into said inlet, means for impregnating cellulose- V bearing material with a chemical solution during its passage to the digesting chamber, the construction being such that the plunger is adapted to compact impregnated cellulose-bearing material through the tapered inlet in the form of a compressed column adapted to form a closure to withstand pressure in the digesting chamber andv act as intermittently advancing cork.

24. A digesting apparatus including in combination a digesting chamber, an elongated ta;

pered inlet for said chamber, means for introducing cellulose-bearing material into said inlet, a reciprocatingv plunger adapted to reciprocate into said inlet, means for impregnating cellulosebearing material with a chemical solution during its passage tothe digesting chamber, the construction being such that the plunger is adapted to compact impregnated cellulose-bearing material through the tapered inlet in the form of a compressed column adapted to form a closure to withstand pressure in the digesting chamber and act as an intermittently advancing cork,

said tapered inlet comprising a converging- 25. An apparatus for the manufacture of pulpv comprising a treating vessel, an 'mletfor feeding material into the vessel, the vessel being of relatively great length with respect to its diameter and with respect to the length of the inlet, and feeding mechanism for urging material through said inlet, said feeding mechanism and inlet cooperating, to compact the material in the inlet to forml a plug unsupported except by the inlet walls,` said plug having a density of` at least twenty pounds of dry materiai to the cubic foot.l l

26. An apparatus for the manufacture of pulp comprising a. treating vessel, an inlet for feeding material into the vessel, the vessel being of relatively great length with `respect to its diameter and with respect to the length of the inlet, and reciprocating feeding mechanism for urging material through said inlet, said feeding mechanism and inlet cooperating to compact the material to form an internally unreinforced plug, saidplughaving a density of at least twenty pounds of drymaterial to the cubic foot.

27. A continuous digester 'for pulping nbrous or cellular material having its inlet closed by a plug having a density of at least twenty pounds of dry material per -cubic foot and comprising the material being digested.

28. A`continuous digester for the pulping of fibrous or cellular material closed at its end by an internally unreinforced plug comprising material to be digested, saidy plug having a length at least twice its width, being unsupported except by the inlet walls and having a density of at least twenty pounds of dry material per cubic foot.

JOAQUIN JULIO nl: LA ROZA, SR. 

